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In the website settings your-domain/admin/settings/payments add a new Payment method CCBillFlexForm;
Fill in:
a. Account ID;
b. Sub Account ID;
c. FlexForm ID;
d. Salt Key (you can find it in your CCBill settings Account Info → Sub Account Admin → --Advanced → Encryption Key);
Click “Save”;
FlexForm is configured.
Notify ccbill support to enable CORS from your website
Send them your website url and request to enable CORS requests sent to https://api.ccbill.com/payment-tokens/merchant-only payment url